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Paxos and other consensus algorithms and the unaccountable love for asynchrony
I’ve been looking at Paxos and Raft and Zab and other algorithms that can loosely be called “consensus” algorithms because we want to see where we can improve distributed system operation with precision time synchronization or where we can offer novel features because of precision timing. Google’s Spanner database is an interesting example in this area but…
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Keynes apology
The composition of this book has been for the author a long struggle of escape, and so must the reading of it be for most readers if the author’s assault upon them is to be successful,—a struggle of escape from habitual modes of thought and expression. The ideas which are here expressed so laboriously are…
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Process algebra is based on a misunderstanding of automata theory
See the current pdf in Arxiv Robin Milner’s book Communication and Concurrency involves a take on state machines that is fundamentally incorrect. “Now in standard automata theory, an automaton is interpreted as a language i.e. as a set of strings over the alphabet.“ That’s not at all correct, but let’s accept the claim for now…
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More on Fischer, Lynch, Patterson and the parrot theorem.
I’m thinking about distributed consensus algorithms, timestamping, and databases and if you read that literature you will see many references to the Fischer, Lynch, Paterson “theorem”. Google Scholar tells me the paper has been cited more than 4500 times. The theorem can be paraphrased as the following If you cannot tell the difference between a network…
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ESMA clarifies time sources for MiFID II
ESMA just released guidelines that reinforce what was already clear in the MiFIDII regulation – that GPS time is a perfectly acceptable source of “traceable” time. There is a lot else that is of interest in this report, but it’s a good reminder to not be panicked by marketing scare-tactics. As per Article 1 of…
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Practical State Machines for Computer Software and Engineering
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Theories of abstract automata – Arbib
We have said that automata theory deals with the realization of partial functions F: X* —» Y* by some finitely specifiable substrate. Before we specify in more detail the forms (of which the Turing machine is one) of substrate which have figured most prominently in automata theory, it is useful to distinguish on-line machines from…
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MiFID II, GPS and UTC time
I have a post up on FSMLabs web site about the use of GPS and other satellite time for MiFID II timestamp compliance. It’s fascinating how much effort has recently gone into trying to convince people that MiFID II will require direct time from a national lab or certified via a national lab despite the…
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Kirkhart’s conjecture